id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
36050	Cannot resolve OuterRef to CompositePrimaryKey	Jacob Walls	Csirmaz Bendegúz	"With CompositePrimaryKey, using `OuterRef(""pk"")` in a subquery raises ValueError. Not certain if this is a release blocker or a new feature. If it's a new feature, we might want to document that it's not currently supported.

{{{#!diff
diff --git a/tests/composite_pk/test_filter.py b/tests/composite_pk/test_filter.py
index 7e361c5925..c3dfc8d44b 100644
--- a/tests/composite_pk/test_filter.py
+++ b/tests/composite_pk/test_filter.py
@@ -1,3 +1,4 @@
+from django.db.models import OuterRef, Subquery
 from django.test import TestCase
 
 from .models import Comment, Tenant, User
@@ -54,6 +55,12 @@ class CompositePKFilterTests(TestCase):
             with self.subTest(lookup=lookup, count=count):
                 self.assertEqual(User.objects.filter(**lookup).count(), count)
 
+    def test_outer_ref_pk(self):
+        qs = Comment.objects.filter(
+            id__gt=Subquery(Comment.objects.filter(pk=OuterRef(""pk"")).values(""id"")[:1])
+        )
+        self.assertEqual(qs.count(), 0)
+
     def test_order_comments_by_pk_asc(self):
         self.assertSequenceEqual(
             Comment.objects.order_by(""pk""),
}}}
{{{
  File ""/Users/.../django/django/db/models/fields/tuple_lookups.py"", line 32, in get_prep_lookup
    self.check_rhs_is_tuple_or_list()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File ""/Users/.../django/django/db/models/fields/tuple_lookups.py"", line 39, in check_rhs_is_tuple_or_list
    raise ValueError(
        f""{self.lookup_name!r} lookup of {lhs_str} must be a tuple or a list""
    )
ValueError: 'exact' lookup of 'pk' must be a tuple or a list
}}}
----
Adjusting the guard that raises ValueError to also accept `ResolvedOuterRef` leads to a more interesting failure:
{{{
  File ""/Users/.../django/django/db/models/expressions.py"", line 1162, in as_sql
    val = output_field.get_db_prep_value(val, connection=connection)
  File ""/Users/.../django/django/db/models/fields/related.py"", line 1161, in get_db_prep_value
    return self.target_field.get_db_prep_value(value, connection, prepared)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/Users/.../django/django/db/models/fields/__init__.py"", line 2819, in get_db_prep_value
    value = self.get_prep_value(value)
  File ""/Users/.../django/django/db/models/fields/__init__.py"", line 2129, in get_prep_value
    raise e.__class__(
        ""Field '%s' expected a number but got %r."" % (self.name, value),
    ) from e
TypeError: Field 'id' expected a number but got Col(composite_pk_comment, composite_pk.Comment.tenant).
}}}"	Bug	closed	Database layer (models, ORM)	dev	Release blocker	fixed	subquery	Csirmaz Bendegúz	Ready for checkin	1	0	0	0	0	0